Endovascular Fistula Device With Self-Sealing Fibrous Puncture Layer
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Solution Overview
Problem
Current endovascular devices for hemodialysis fistulas are prone to damage and fail due to repeated punctures, leading to complications such as stenosis, occlusion, and thrombosis, and existing stent-grafts are unsuitable for frequent needle punctures, limiting their effectiveness and longevity.
Innovation Solution
An endovascular device with a fibrous layer containing long nanofibers and expandable sections that self-seal after punctures, adhering to vessel walls and maintaining patency through endothelialization, allowing repeated use without damaging the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If current stent-grafts with ePTFE sheath and nitinol skeleton are used in hemodialysis fistulas, then structural support and patency maintenance are improved, but the device becomes vulnerable to needle puncture damage and permanent hole formation
Solution Approach 1:
The patent replaces the rigid ePTFE sheath with a flexible biological tissue layer that can elastically deform during needle puncture and automatically seal the puncture site. This flexible biological shell maintains structural support while eliminating the permanent hole problem of conventional ePTFE sheaths.
Solution Approach 2:
The patent changes the material parameter from synthetic ePTFE to biological tissue with elastomeric properties, enabling the sheath to exhibit elastic deformation and self-sealing behavior rather than permanent deformation. This parameter change transforms the material's response to needle puncture from damage to reversible deformation.
2Productivity
If repeated needle punctures are performed on conventional stent-grafts, then hemodialysis treatment can be maintained, but the device suffers from cumulative damage leading to breakage or deformation
Solution Approach 1:
The biological tissue layer provides self-service by automatically sealing puncture sites through its elastomeric properties, eliminating the need for external repair or replacement after each puncture. This self-sealing mechanism allows the device to maintain functionality indefinitely despite repeated punctures.
Solution Approach 2:
The flexible biological tissue layer acts as a cushioning element that absorbs the mechanical stress of needle puncture before it can reach and damage the nitinol skeleton. This prior cushioning prevents cumulative damage and extends device lifespan.
3Ease of operation
If angioplasty is performed as first-line treatment for non-functioning fistulas, then initial patency can be restored, but long-term patency rates remain low due to recurrent stenosis and thrombosis
Solution Approach 1:
The patent creates a composite structure combining the radial support of nitinol skeleton with the self-sealing and biocompatible properties of biological tissue layer. This composite material provides both the mechanical support needed to prevent stenosis and the biological properties that reduce thrombosis risk, achieving high long-term patency rates.
Solution Approach 2:
The biological tissue layer acts as an intermediary between the nitinol skeleton and the blood flow, providing a biocompatible surface that reduces thrombogenicity while the nitinol provides structural support. This intermediary layer mediates between mechanical support requirements and biological compatibility.
4Reliability
If stent placement is used to maintain fistula patency, then long-term patency improves, but a portion of the superficial venous circuit must be excluded from use
Solution Approach 1:
The device provides multiple functions within a single structure: the nitinol skeleton provides radial support to maintain patency, while the flexible biological tissue layer enables repeated needle punctures and self-sealing. This multi-functionality allows the entire venous circuit to remain usable for hemodialysis access, eliminating the need to exclude portions of the circuit.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device maintains fistula patency and prevents bleeding by self-sealing after punctures, extending the lifespan of dialysis access sites and reducing complications.
Implementation Method 1
the puncture of a needle involves a high puncture probability of damaging the nitinol skeleton by breaking or deforming it, and leaves a permanent hole in the ePTFE sheath with the subsequent risk of bleeding, the ePTFE not behaving as a real elastomer
Implementation Method 2
maintaining patency through endothelialization
Data Source
AI summary
The endovascular device (1) according to the invention comprises a first tubular sheath in turn comprising a fibrous layer (5) made of a fibrous material containing a coherent assembly of fibers. The ends of the device (1) form two expansion sections (7A, 7B) each of which in turn comprises an expander device (70) arranged to radially expand the endovascular device (1) at least in correspondence with the respective expansion section (7A, 7B). The fibrous layer (5), in particular in correspondence with the intermediate section (11) is, on the other hand, prickable and capable of quickly closing and resealing the holes produced by the needles for dialysis, transfusions or injections. This feature allows (20) compared to current devices, to treat malfunctioning dialysis fistulas and to avoid the exclusion of a part of the superficial venous circuit potentially usable for the hemodialysis session, so that the device being a maintenance device for fistulas from dialysis.